DIFFERENTIAL EFFECTS OF STRENGTH TRAINING LEADING TO FAILURE VERSUS NOT TO FAILURE ON HORMONAL RESPONSES, STRENGTH AND MUSCLE POWER GAINS.
Izquierdo M, Ibanez J, Gonzalez-Badillo JJ, Hakkinen K, Ratamess NA, Kraemer WJ, French DN, Eslava J, Altadill A, Asiain X, Gorostiaga EM.
Studies, Research and Sport Medicine Center, Government of Navarra, Pamplona, Navarra, Spain.
The purpose of this study was to examine the efficacy of 11 weeks of resistance training to failure vs. non-failure, followed by an identical 5- week peaking period of maximal strength and power training for both groups as well as to examine the underlying physiological changes in basal circulating anabolic/catabolic hormones. Forty-two physically-active men were matched and then randomly assigned to either a training to failure (RF; n=14), non-failure (NRF; n=15) or control groups (C;n=13). Muscular and power testing and blood draws to determine basal hormonal concentrations were conducted before the initiation of training (T0), after 6 wk of training (T1), after 11 wk of training (T2), and after 16 wk of training (T3). Both RF and NRF resulted in similar gains in 1RM bench press (23% and 23%) and parallel squat (22% and 23%), muscle power output of the arm (27% and 28%) and leg extensor muscles (26% and 29%) and maximal number of repetitions performed during parallel squat (66% and 69%). RF group experienced larger gains in the maximal number of repetitions performed during the bench press The peaking phase (T2 to T3) followed after NRF resulted in larger gains in muscle power output of the lower extremities, whereas after RF resulted in larger gains in the maximal number of repetitions performed during the bench press. Strength training leading to RF resulted in reductions in resting concentrations of IGF-1 and elevations in IGFBP-3, whereas NRF resulted in reduced resting cortisol concentrations and an elevation in resting serum total testosterone concentration. This investigation demonstrated a potential beneficial stimulus of NRF for improving strength and power, especially during the subsequent peaking training period, whereas performing sets to failure resulted in greater gains in local muscular endurance. Elevation in IGFBP-3 following resistance training may have been compensatory to accommodate the reduction in IGF-1 in order to preserve IGF availability.
L'entrainement NOT TO FAILURE semble tout à fait efficace (meme gains de force un peu moins d'endurance), mais je me demande à combien de reps ils restaient de l'échec ca aurait été bien d'avoir des détails... mais avec mon expérience de rest-pause folles, je me rends compte qu'aller à l'échec et au dela n'est pas utile et peut meme etre contreproductif. J'essayerais de trouver plus d'études sur les entrainements TF (to failure) versus NTF (not to failure).
Hormonalement d'après ce que je comprends l'entrainement NTF aurait meme l'avantage... peutêtre une indication du fait que s'entrainer à l'échec va conduire à l'overtraining (hormonal) plus vite !?
Etude Bonus : Positif ou Negatif meme effet hormonal
Bottom Line, it makes nil of a difference so for all those Guru's who constantly say GH is greater with conentric, forget it.
Similar hormonal responses to concentric and eccentric muscle actions using relative loading.
Kraemer RR, Hollander DB, Reeves GV, Francois M, Ramadan ZG, Meeker B, Tryniecki JL, Hebert EP, Castracane VD.
Department of Kinesiology and Health Studies, Southeastern Louisiana University, SLU 10845, Hammond, LA, 70402, USA, rkraemer@selu.edu.
Conventional resistance exercise is performed using sequential concentric (CON) and eccentric (ECC) contractions, utilizing the same muscle load. Thus, relative to maximal CON and ECC resistance, the ECC contraction is loaded to a lesser degree. We have recently shown that at the same absolute load, CON contractions are associated with greater growth hormone (GH) but similar total testosterone (TT) and free testosterone (FT) responses compared with ECC contractions and attributed the larger GH response to greater relative CON loading. In the present study, we have examined the same endocrine parameters to six different upper and lower body exercises using relative loading rather than absolute loading, hypothesizing that GH responses would be similar for CON and ECC actions, but TT and FT responses would be greater after ECC contractions. Seven young men with recreational weight training experience completed an ECC and CON muscle contraction trial on two different occasions in a counterbalanced fashion. The exercises consisted of four sets of 10 repetitions of lat pull-down, leg press, bench press, leg extension, military press, and leg curl exercises at 65% of an ECC or CON 1-RM with 90 s between sets and exercises. CON and ECC actions were performed at the same speed. ECC 1-RMs were considered to be 120% of the CON 1-RM for the same exercise. Blood samples were collected before, immediately after, and 15 min after the exercise. GH significantly increased across both trials but was not different between the two trials. Total testosterone was not significantly altered in response to either trial; however, free testosterone concentrations increased in response to both ECC and CON trials. Data suggest that CON and ECC muscle contractions produce similar GH, T, and free testosterone responses with the same relative loading.
. Pour la similitude concentrique/excentrique je ne suis pas étonné, le muscle s'en branle dans quel sens il bouge, même s'il bouge pas il cherche à s'adapter 
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et je l'espère comprendra aussi la relation qui existe entre la force et les muscles !
